The invention is an integrated thermochemical process, also known as a looped-oxide catalysis, for providing an upgraded biofuel composition from a biomass-derived feedstock. First, the feedstock is deoxygenated through reaction with a low-valence metal oxide or zero-valent metal to yield a deoxygenated biofuel composition and a high-valence metal oxide. Second, the low-valence metal oxide is regenerated by reducing the high-valence metal oxide using solar thermal energy.
Instabilities in the price of petroleum and the impact of fossil fuel combustion on global climate change demand that a clean and renewable source of transportation fuels be developed; particularly one that will not require major changes to the existing infrastructure of fuel consumption. Given their high energy density it is likely that liquid hydrocarbon fuels will play a dominant role in the foreseeable future of the ever-expanding transportation industry.
While petroleum-derived fuels constitute the bulk of transportation fuels currently in use, there are many available fuel upgrade paths for converting cellulosic biomass into value-added fuels including Fischer-Tropsch synthesis and hydrodeoxygenation (HDO) or zeolite upgrading of bio-oils. In general, cellulosic biomass feedstocks represent a good starting material for liquid fuel production but such feedstocks typically have high oxygen contents and, consequently, low combustion energy densities. At the same time, alternative energy sources such as solar, wind and geothermal power are gaining traction in the energy industry but are generally limited to supplying electrical energy to the grid. Solar energy is the largest exploitable renewable resource by far; the energy available from terrestrial insolation far exceeds the needs of human consumption.
Bio-oils obtained from the thermal processing of cellulosic biomass represent a promising feedstock for the production of renewable fuels; however, without deep upgrading their direct use as a fuel is extremely limited. Therefore the development of hydroprocessing technologies for the upgrading of bio-oils to utilizable transportation fuels is of great importance. Hydroprocessing involves the addition of hydrogen gas into a low-grade liquid fuel in the presence of a solid catalyst. The goal of hydroprocessing is to improve fuel quality by removal of heteroatoms, resulting in higher energy content, volatility and thermal stability and lower viscosity and molecular weight. Because oxygen is the predominant heteroatom in bio-oils, studies on bio-oil hydroprocessing tend to focus on hydrodeoxygenation (HDO) as the primary reaction pathway.
There are two principal avenues leading from raw cellulosic biomass to bio-oils: fast pyrolysis and liquefaction. Fast pyrolysis is the rapid thermal decomposition of biomass in the absence of oxygen. Liquefaction is the decomposition of biomass in hydrothermal media. Due to their high oxygen content both fast pyrolysis and liquefaction oils are generally unusable without deep upgrading.
It would therefore be desirable to provide a more efficient and optimized process for providing an upgraded biofuel composition from a feedstock.